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Open access

Nam-Sun Son, Sun-Yonug Kim and Chan-Soo Lee

Abstract

To reduce crewmembers’ error and increase the safety of ships’ navigation, a recognition system of collision risks among multiple ships is newly-developed. By using ships’ navigational information such as AIS data, an algorithm to calculate collision risks among multiple ships is newly-designed. Collision risks of multiple ships can be estimated considering ships’ position and course of now and future by using fuzzy algorithm. To evaluate the performance of new system, replay simulation is carried out by using actual AIS data of actual collision accident in Korea. In this paper, main features of the monitoring system of collision risks and the results of replay simulation are discussed.

Open access

Hyun-Soo Kim, Chun-Ju Lee, Kyung-Sik Choi and Moon-Chan Kim

ABSTRACT

A full-scale field trial in ice-covered sea is one of the most important tasks in the design of icebreaking ships. The first Korean icebreaking research vessel ‘ARAON’, after her delivery in late 2009, had a sea ice field trial in the Arctic Sea during July-August, 2010. This paper describes the test procedures and data analysis on the icebreaking performance of the IBRV ARAON. The data gathered from the icebreaking performance test in the Chukchi Sea and the Beaufort Sea during the Arctic voyage of ARAON includes the speed and engine power of the ship as well as sea ice thickness and strength data. The air temperature, wind speed and heading of the ship were also measured during each sea ice trial. The ARAON was designed to break 1 m thick level ice with a flexural strength of 630kPa at a continuous speed of 3knots. She is registered as a KR POLAR 10 class ship. The principal dimensions of ARAON are 110 m, 19 m and 6.8 m in length, breadth and draft respectively. She is equipped with four 3,500kW diesel-electric main engines and two Azipod type propulsion motors. Four sea ice trials were carried out to understand the relationship between the engine power and the ship speed, given the Arctic ice condition. The analysis shows that the ARAON was able to operate at 1.5knots in a 2.5m thick medium ice floe condition with the engine power of 5MW, and the speed reached 3.1 knots at the same ice floe condition when the power increased to 6.6MW. She showed a good performance of speed in medium ice floe compared to the speed performance in level ice. More detailed analysis is summarized in this paper.

Open access

Museok Song, Moon-Chan Kim, In-Rok Do, Shin Hyung Rhee, Ju Hyun Lee and Beom-Soo Hyun

ABSTRACT

Three types of 100 kW-class tidal stream turbines are proposed and their performance is studied both numerically and experimentally. Following a wind turbine design procedure, a base blade is derived and two additional blades are newly designed focusing more on efficiency and cavitation. For the three designed turbines, a CFD is performed by using FLUENT. The calculations predict that the newly designed turbines perform better than the base turbine and the tip vortex can be reduced with additional efficiency increase by adopting a tip rake. The performance of the turbines is tested in a towing tank with 700 mm models. The scale problem is carefully investigated and the measurements are compared with the CFD results. All the prediction from the CFD is supported by the model experiment with some quantitative discrepancy. The maximum efficiencies are 0.49 (CFD) and 0.45 (experiment) at TSR 5.17 for the turbine with a tip rake.